ouo.io: a standard ad wall
ouo.io uses a fairly typical flow: a countdown, a 'get link' button and a page or two of ads. It is a standard-tier shortener, which means resolving it is quick and reliable.
In practice an ouo.io link resolves in just a few seconds. You skip the timer and the ad pages and land on the real destination almost immediately.
exe.io: a heavier, premium wall
exe.io (and its sibling cuty.io) layers on a tougher challenge, including a captcha-style check before the link is released. We treat it as a premium-tier wall.
That extra protection takes longer to clear, so an exe.io resolve can run up to about twenty seconds. The live progress on screen shows you it is working through the steps.
Which is faster to skip
If speed is all you care about, ouo.io resolves faster because its wall is lighter. exe.io is slower but still fully resolvable, you just wait a little longer for the protected step to clear.
Either way the outcome is the same: the real destination with no ads. Open the ouo.io or exe.io guide to skip them yourself.